The present invention relates to an interactive, chargeable communication system with a billing system for chargeable program which may be obtained by compressing video or audio information, a character information, data or application program and transmitted from a multi-channel program communication service company, etc., through an interactive communication cable, ground wave, satellite wave or telephone line, etc., for the purpose of, for example, program request and home shopping, etc. Particularly, the present invention relates to a chargeable broadcasting system in which a user receiving a scrambled program can watch and/or hear a program by descrambling the program by using a dedicated decoder while paying therefor based on Pay-Per-View (PPV) system in which only program received by the user is billed.
Beside the conventional ground broadcasting in which a program video is transmitted to respective homes through the use of VHF or UHF wave, a cable broadcasting for directly transmitting program from a relay transmitter to respective home terminals by using cables such as coaxial cables or optical cables extending therebetween is becoming popular and, particularly, a number of cable broadcasting enterprises are being established for providing multi-channel services owing to the fact that transmission of programs using communication satellites or broadcasting satellites becomes possible recently.
Further, with developments of optical fiber technology, digital transmission technology and high efficiency coding technology, a communication service such as entertainment program delivery system, etc., which may substitute for the rental video and in which a desired program is viewed at desired time by program request using interactive communication cable, such as home shopping or Video-On-Demand (VOD) program, have been studied.
Such cable broadcasting or VOD system transmits video signal through a coaxial cable, etc. Therefore, there is no radio fault such as ghost which occurs frequently in the program broadcasting using ground wave. Further, such system can be used for a re-transmission of a usual program delivered by using ground wave and for broadcastings specific to program delivery companies.
Each viewer makes a contract with service companies of such as VOD and can view the re-transmission of program of the ground wave broadcasting supplied by cable broadcasting companies or service companies without radio fault by connecting a dedicated receiving terminal to his video signal display device such as television receiver. Further, it becomes possible to view film drama, various sports relayed and music programs from such companies without using any special equipment other than the dedicated terminal. Further, by connecting a video signal recording/reproducing apparatus such as VTR to the dedicated terminal, it is possible to record these programs.
On the other hand, the service company transmits program video software to only the viewers who made contract with it. Therefore, for the service company, it is desired to provide their programs to only viewers which made contract with it and are chargeable. That is, any system according to which unauthorized viewers who did not make contract with a service company can view programs supplied by the company is not desired by the service company. In the conventional system, it is impossible for any one having no dedicated terminal to directly receive programs from such service company and view them on a television receiver. However, when a program received by a dedicated terminal is copied by using, for example, a VTR, the copy can be viewed easily by any one who has no dedicated terminal. That is, in the conventional system, it is impossible to prevent such unauthorized view of programs supplied from a service company.
In the BS standard scrambling system disclosed in, for example, K. Kobayashi, "1-2 Scrambled Broadcasting by BS", the Journal of Television Engineers Society, Vol. 46, No. 4. pp. 387 to 391 (1992), a content of program is scrambled and a viewer who makes contract with a broadcasting company for each channel views it by descrambling the program by means of a dedicated decoder.
The billing in the disclosed system is based on the Flat-Fee system in which a constant viewing fee is charged for all programs. On the other hand, there is another billing system called Pay-Per-View (PPV) in which a viewer views only program he wants to see and pays a fee for it. The PPV is classified to Pay-Per-Time (PPT) in which a viewer is charged for time for which he viewed the program and Pay-Per-Program (PPP) in which a viewer is charged for each program he viewed and the PPP is sub-classified to Video-On-Demand (VOD) in which program data requested by each viewer is transmitted to him and Near-Video-On-Demand (NVOD) in which a viewer selects any of channels on which a single program is continuously broadcasted with broadcasting time being shifted.
In a chargeable broadcasting using the PPP billing system, it may be considered that programs scrambled in any of a plurality of ways are broadcasted through a single channel and a viewer selects any of the programs, descrambles it and is charged for the selected and descrambled program. In such case, it is enough for a broadcasting side to merely broadcast the respective scrambled programs in sequence. However, a viewer must reconfirm contents of the programs by temporarily stopping them and, when he wants to view any or some of them, he must re-view the same program or programs by paying fee therefor or he must record data thereof on such as VTR while he is viewing it.
On the other hand, in CATV service, data is time-axis compressed and transmitted to each subscriber who stores the data in a digital recording device such as digital VTR (DVTR) and views it after decompression as in VOD. Since, in this case, it is possible to reproduce the recorded digital data at any time repeatedly without degradation, there may be a problem of infringement of copyright of a producer of the program.
Therefore, in such chargeable broadcasting, a new billing system must be provided by taking the unauthorized recording of digital data and the unauthorized dubbing into consideration. This problem may be solved by detecting a descrambling processing for a data received or reproduced from the DVTR and input to a decoder for descrambling and billing an owner of the decoder on the basis of the descrambling processing, since all views are billed and collection of fee is possible corresponding to a state of viewing.
In this case, however, since the billing side can not determine program content reproduced from the VTR when a viewer views it by means of DVTR, the PPP billing system can not be applied thereto. In addition, when a special reproduction of a program such as temporary stop, etc., in VTR, the same program is reproduced intermittently and therefore the number of views can not be determined clearly, causing determination of object to be billed to be difficult.
In view of these problems, it is effective to employ a billing system in which, for a program which is selected by a subscriber, the subscriber is given a permission of viewing the program for a time period measured in specific time unit, that is, the subscriber is permitted to descramble the program for the time period and he is billed in program unit within the time period rather than the number of views, as in the current cassette rental system of video software. This system is disclosed in, for example, Japanese Patent Application Laid-open (Kokai) No. H5-284499.
The interactive cable television in which an information, such as video or audio, character information or data, requested by a terminal connected to a network is scrambled by compressing it and transmitted to the terminal through the network is disclosed in, for example, Y. Mochida, "Digital Optical Cable TV", the Journal of Television Engineers Society, Vol. 47, No. 8. pp. 1082 to 1087 (1993).
In the above article, although the technology concerned to the system and services of such interactive cable television is disclosed, there is no disclosure about the billing system for subscribers having such terminals and the copyright protection.